The invention relates to the technical field of electronic circuits, and discloses a monitoring circuit, a battery and an aircraft. The monitoring circuit comprises a supply voltage input terminal, asupply voltage is applied to the supply voltage input terminal; A voltage holding circuit connected to a supply voltage input terminal; A first comparison circuit respectively connected to a supply voltage input terminal and a voltage holding circuit; A second comparison circuit respectively connected with a supply voltage input terminal and a voltage holding circuit; A protection circuit connected to the first comparison circuit and the second comparison circuit, respectively, and connected to a reset pin of the processor; When the supply voltage exceeds the preset voltage range, The first comparing circuit and the second comparing circuit output a high level or the first comparing circuit and the second comparing circuit output a low level so as to make the protection circuit output a low level, so that the reset pin of the processor is pulled low, and the processor is triggered to enter a reset state, so that the program of the processor is prevented from being tampered with when the power supply voltage fluctuates.